Corixa and Lorantis Announce Joint Collaboration to Develop Therapeutic Hepatitis B Vaccine.

SEATTLE and CAMBRIDGE, United Kingdom -- Corixa Corporation (Nasdaq:CRXA), a developer of immunotherapeutics, and Lorantis, a Cambridge, U.K.-based immunotherapy company, today announced a joint collaboration in which the companies will continue the development of a therapeutic hepatitis B vaccine, containing Corixa's RC-529(TM) adjuvant and Lorantis' CV-1831, a hepatitis B core antigen that was previously owned by Apovia, Inc.

This collaboration builds on the initial research and development conducted by Corixa and Apovia for the development of a therapeutic vaccine for the treatment of hepatitis B. Lorantis has acquired all of Apovia's interest in the hepatitis B vaccine technology and under the terms of the new agreement, Lorantis will assume many of Apovia's development responsibilities. The collaboration is managed by a joint management team where Corixa will take the lead for the regulatory applications and management of all clinical trials. Lorantis will lead the completion of preclinical studies and supply the hepatitis B core antigen. The companies will share equally in all costs and potential revenues associated with the development of the vaccine. Following proof-of-principle clinical trials, the companies intend to partner the vaccine to a late-stage development and commercialization organization.

"We are pleased to partner with Lorantis to build on the progress we have made under our original agreement with Apovia," said Steven Gillis, Ph.D., chairman and chief executive officer of Corixa. "Our collaboration with Lorantis will allow us to pursue clinical development of a therapeutic hepatitis vaccine powered by our RC-529 adjuvant."

"This partnership with Corixa should ensure that CV-1831 will be competitively developed," said Stefan Fischer, chief executive officer of Lorantis. "Our investment in this therapeutic hepatitis B vaccine is the first step to transform Lorantis from a research driven company into a development focused company as we build our immunology portfolio."

About Hepatitis B

Hepatitis B is the most common serious liver infection in the world. It is caused by the hepatitis B virus that attacks the liver. The virus is transmitted through blood and infected bodily fluids. This can occur through direct blood-to-blood contact, unprotected sex, use of unsterile needles, and from an infected woman to her newborn during the delivery process. According to the hepatitis B Foundation, hepatitis B can be 100 times more infectious than the AIDS virus. More information is available at http://www.hepb.org.

About Corixa's Adjuvant Business

Corixa's adjuvant technology is based on the fact that certain microbial products have long been recognized as potent immune system regulators and have been shown to induce a broad range of known cytokines, a class of substances that are produced by cells of the immune system and can affect the immune response. Modifications of these microbial products and their physical and biological delivery to the immune system can influence the way cytokines are expressed, as well as the recipient's own physiological responses. Such responses mimic the normal, protective responses that are initiated during microbial infection or injury. RC-529 is Corixa's lead synthetic adjuvant that can be formulated for a variety of applications including intranasal and pulmonary vaccines.

About Corixa

Corixa is a biopharmaceutical company developing vaccine adjuvants and immunology based products that manage human diseases. Corixa's products are currently in multiple clinical development programs, including several that have advanced to and through late stage clinical trials. The company partners with numerous developers and marketers of pharmaceuticals, targeting products that are Powered by Corixa(TM) technology with the goal of making its potential products available to patients around the world. Corixa was founded in 1994 and is headquartered in Seattle, with additional operations in Hamilton, Montana. For more information, please visit Corixa's Web site at www.corixa.com.

About Lorantis

Lorantis is pursuing immunology drug discovery and development through a unique molecular mechanism, Notch, that can be targeted to enhance or suppress antigen-specific immune responses. The company has two broad platforms to generate multiple products in areas of high unmet medical need. Antigen-specific immune suppressors are being developed for the treatment of allergy, asthma, autoimmune diseases and transplant rejection. By enhancing the immune response, Lorantis is addressing cancer and infectious diseases. The company has received venture backing from Apax Partners, Abingworth Management, Schroder Ventures Life Sciences, JP Morgan Partners, Quester, The Wellcome Trust and Northern Venture Managers. Lorantis was established in 1998 and is based in Cambridge, U.K. For more information, please visit Lorantis Web site at www.lorantis.com.

Corixa Forward-Looking Statements

This press release contains forward-looking statements, including statements regarding the potential development of a hepatitis B vaccine, and other statements regarding our plans, objectives, intentions and expectations. Forward-looking statements are based on the opinions and estimates of management at the time the statements are made. They are subject to certain risks and uncertainties that could cause actual results to differ materially from any future results, performance or achievements expressed or implied by such statements. Factors that could affect Corixa's actual results include, but are not limited to, the "Factors Affecting Our Operating Results, Our Business and Our Stock Price," described in our Quarterly Report on Form 10-Q for the quarter ended September 30, 2004, copies of which are available from our investor relations department. Readers are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date of this release.